1. Field of the Invention
This invention relates to the art of electrochemical cells, and more particularly, to a new and improved electrochemical cell, and cathode therefor, comprising a Group IA anode and a composite metal-metal-metal oxide cathode.
Light metals have exceptionally high energy density when employed as the anode material in electrochemical cells owing to their low atomic weight and to the high standard potential of the cells. This high chemical activity of light metal anode material requires the use of a nonaqueous electrolyte and a cathode which meets the rigorous requirements for such a cell. Most cathode materials are too readily soluble in a nonaqueous electrolyte and, thereby, reduce the useful capacity of such an electrode after storage. The cathode material of the present invention uses a mixed metal oxide containing copper, silver, and vanadium as an electrode material for application as a cathode in a lithium battery. This provides a new and distinct cathode material having the general formula Cu.sub.x Ag.sub.y V.sub.2 O.sub.z, also referred to herein as CSVO.
2. Prior Art
It is known to use metal oxides as cathode materials in nonaqueous electrochemical cells. For example, U.S. Pat. No. 4,310,609 Liang et al., which is assigned to the assignee of the present invention and incorporated herein by reference, discloses the use of a composite cathode material including V.sub.2 O.sub.x wherein x.ltoreq.5 combined with one or more of Ag.sub.2 O.sub.x wherein x=0 to 1; CuO.sub.x wherein x=0 to 1; and MnO.sub.x wherein x=1 to 3. The composite material is described as a metal oxide-metal oxide, a metal-metal oxide, or a metal-metal oxide-metal oxide. A preferred embodiment of this cathode material has the formula AgV.sub.2 O.sub.5.5, also referred to herein as SVO.
While this prior art battery material works well, the cathode material of the present invention provides an increased gravimetric energy density and an increased pulse voltage delivery capacity. This makes the cathode material of the present invention particularly useful for implantable medical applications. The CSVO material of the present invention is also an improvement over SVO cathode material in savings on the expense of the silver starting material.